The angle of incidence is 0 degrees when a beam of light falls properly on the surface of a flat mirror. We know that the angle of incidence equals the angle of reflection because of reflection rules. As a result, the angle of reflection will be zero as well. As a result, the light returns in the same direction.
What happens when a ray of light falls normally on the surface of a plane mirror?
What happens when a ray of light falls normally on the surface of a plane mirror?